1. Field of the Invention
The present invention relates to a seat slide device which supports a seat in order that the seat is slidable therealong forwardly and backwardly and permits for adjusting such forward and backward movement of the seat.
2. Description of Prior Art
A seat for use in an automobile or the like is in most instances slidable for adjustment of its position in the forward and backward directions by means of a seat slide device.
Reference is made to FIGS. 1(A) and 1(B) showing an example of conventional seat slide device (210) which is comprised of a lower rail (214) fixed on a floor of an automobile (not shown) and an upper rail (218) fitted in the lower rail (214) slidably via steel balls (216).
The two bifurcated ends of the upper rail (210) are each formed with an inwardly curved part (228), and both lateral walls of the lower rail (214) are each formed with an outwardly curved part (222). Those two inwardly and outwardly curved parts (228) (222) cooperate to retain each of the balls (216) therein. Generally, the steel balls (216) are so arranged that one of them is disposed at a forward portion of the rails and another of them at a backward portion thereof with a certain space therebetween. The balls (216) of course serves to facilitate the slidability of the upper rail (218) along the lower rail (214). As shown, in this slide rail device, the lower rail (214) is bent it its two upper end portions into an inverted U-shaped section (234), while the upper rail (210) is formed with a horizontal section (230). This arrangement prevents separation of the upper rail (210) from the lower one (214), because, if an upward excessively great force is applied to the upper rail (210) through a seat belt in a collision or sudden deceleration case, the upper rail (210) is forced upward away from the lower rail (214), but the horizontal section (230) of the upper rail (210) contacts the downwardly projecting edge of the inverted U-shaped section (234) as shown in FIG. 1(B), thereby preventing removal of the upper rail (210) from the lower one (214).
However, as apparent from FIG. 1(A), in this conventional slide rail, a spacing (L) is given between the inverted U-shaped sections (234) and horizontal section (230), as a result of which, it has been found defective in that (i) the upper rail (210) is merely supported via the balls (216) to the lower rail (214), which makes loose the slidable connection between the inwardly curved part (228) of upper rail (210) and outwardly curved part (222) of lower rail (22) and will emit a noise due to the wobbling of the two rails, (ii) such spacing (L) results inevitably in deformation of the inwardly curved part (228) of upper rail (210) as in FIG. 1(B), and thus it is impossible to avoid damage to the slide rail per se, and (iii) In attempt to avoid such slide rail deformation, one can consider forming longer the downwardly projected edges of lower rail inverted-U-shaped section (234) close to the horizontal section (230) as indicated by phantom line in FIG. 1(A); however, even a slight vibration or rolling of the automobile will easily cause such downwardly projected edges to be contacted with the horizontal section (230), thus resulting in producing an unpleasant noise there.